1. Field of the Invention
The present invention relates to an optical disc apparatus, and more particularly to an optical disc apparatus to perform a time search process to find a desired video data for reproduction.
2. Description of the Related Art
An optical disc of DVD (Digital Versatile Disc)-VIDEO format has recorded thereon a video title(s) which includes cells (data cells) formed of VOBUs (Video Object Units). The video title has MAP_EN (Map Entry) numbers sequentially written thereon and from the beginning thereof at intervals of TMU (Time Unit) which is predetermined and specific to the optical disc, and the data of which is written in VTS_TMAPT (Video Title Set Time Map Table) written in turn on the optical disc. When a search time designated or selected by a user, from which to start reproducing video data in the optical disc and which is time from the beginning of the video title, is input to an optical disc apparatus with an optical pickup (such search time being hereafter referred to as “designated search time”), then the optical disc apparatus calculates a MAP_EN number corresponding to the designated search time based on the TMU written in the VTS_TMAPT.
The optical disc apparatus then reads, from the VTS_TMAPT, the address of a VOBU (Video Object Unit) corresponding to the calculated MA_PEN number, and moves the optical pickup to a position corresponding to the thus read address so as to start reproducing video data in the VOBU. This process is called “time search process”. For example, if the TMU is 2 seconds and the designated search time is 5 seconds, the MAP_EN number is calculated as 2 from the division of 5÷2=2.5. Thus, the optical disc apparatus reads the address of the VOBU corresponding to the MAP_EN number #2 from the VTS_TMAPT, and moves the optical pickup to a position corresponding to the address for video data reproduction. However, since the time search process is performed at the intervals of the TMU, the actual time from which to start the video data reproduction is likely to be offset or shifted from the designated search time.
In the prior art, there are various optical disc apparatus in this field. For example, Japanese Laid-open Patent Publication 2002-271731 discloses an optical disc apparatus to perform a time search process for an optical disc such that the time point of a then or currently performed video data reproduction is used as a reference time so as to find video data positioned at a designated time (period or distance) forward or backward from the reference time. Further, Japanese Laid-open Patent Publication 2005-276439 discloses an optical disc apparatus to perform a time search process for finding video data in an optical disc at a designated search time regardless of the data compression method. However, each of the optical disc apparatus of these patent publications requires that addresses of VOBUs based on predetermined reproduction time distances forward and backward from a VOBU, at which the optical pickup is then or currently positioned, be recorded on the optical disc.